33 research outputs found
Strategies to optimize T cell-based cancer immunotherapy
No full textRemarkable progress has been made in the field of tumor immunology in the past decade but active immunotherapy is not yet an established treatment modality. Tumor associated antigens (TAAs) presented in the form of peptides in association with MHC class 1 can be recognized by T cells and represent major targets of immunotherapy strategies to treat cancer patients. However, ineffective antigen presentation, tumor evasion and T cell tolerance limit anti-tumor immune responses. We have investigated several approaches aimed at improving induction of T cell responses and sensitization of tumor cells to T cell effector mechanisms, which are crucial steps for successful T cell-based immunotherapy.HER-2/neu (HER-2) is a self tumor antigen over-expressed in a variety of tumors and expressed at low levels by normal epithelial surfaces. To enhance the low immunogenicity of HER-2 we developed a series of peptide analogs of the HER-2.369 epitope to improve binding to HLA-A2 We found that one of the analogs (HER-2.369 V2V9) induced cytotoxic T lymphocytes (CTLs) both in vitro and in vivo in HLA-A2/Kb transgenic (tg) mice at 100-fold lower concentration than the wild-type epitope. Importantly, CTLs generated by the analog peptide were also able to recognize the wild-type epitope and HER-2+ tumors in a MHC-restricted manner. The analysis of thermodynamic parameters demonstrated that the high biological activity of the V2V9 peptide variant was associated with a slower dissociation kinetic profile, resulting in an epitope with greater HLA-A2 stability.Next we studied immune responses directed against HER-2 in HLA-A2/Db tg mice upon DNA vaccination. Unexpectedly we found that a DNA vaccine encoding for full length HER-2 protected mice from HER-2+ tumor challenge by a CTL independent mechanism. A strategy aimed at enhancing MHC class 1 processing by a multi-epitope DNA vaccine encoding for 3 HER-2 derived HLA-A2 peptides linked in a "string of epitopes" resulted in high numbers of peptide specific T cells but failed to induce tumor protection. We found that HER-2+ but not HER-2 tumor cells down-regulated MHC class 1 and components of the antigen processing pathway which impaired the capacity to produce and display MHC class 1 peptide-ligands to specific CTLs. These findings are important for the optimization of vaccines targeting HER-2, and suggest that, to be effective, vaccines should aim at inducing an integrated immune response where also CD4+ T cells and antibodies are important components.In searching for new means to improve MHC class I-restricted antigen presentation in malignant cells, we identified retinoic acid (RA) as a modulator of antigen presentation and sensitivity to T cell effector mechanisms in tumor cells. Treatment of neuroblastoma cells with RA resulted in increased expression of MHC class 1 and of proteolytic and regulatory subunits of the immunoproteasome, increased half-life of MHC class 1 complexes and enhanced sensitivity of neuroblastoma cells to both MHC class I-restricted peptide-specific and MHC non-restricted lysis by CTLs. In the next study we extended our investigation of the effects of RA to the uveal melanoma (UM) tumor model. The current therapy of UM metastases is inefficient and the development of new treatment modalities is needed. We found that RA suppresses proliferation and causes morphological changes compatible with differentiation in a panel of UM cells. RA treatment of UM resulted in G I/GO cell cycle arrest which correlated with an increase of p21, p27 and p53 protein levels and with significant down-modulation of the HER-2/neu proto-oncogene surface expression. Unlike neuroblastomas, UM cells failed to up-regulate components of the MHC class 1 antigen processing pathway upon RA-treatment. Nevertheless, RA-treated UM cells exhibited increased sensitivity to both MHC class I-restricted killing by cytotoxic T lymphocytes and NK cell-mediated lysis. These observations could be explained (at least in part) by more efficient conjugate formation between UM cells and killer lymphocytes.Taken together, our findings suggest that the application of retinoids in combination with T cell-based immunotherapy may be an effective therapy for the treatment of neuroblastoma and uveal melanoma.List of scientific papersI. Vertuani S, Sette A, Sidney J, Southwood S, Fikes J, Keogh E, Lindencrona JA, Ishioka G, Levitskaya J, Kiessling R (2004). Improved immunogenicity of an immunodominant epitope of the HER-2/neu protooncogene by alterations of MHC contact residues. J Immunol. 172(6): 3501-8. https://pubmed.ncbi.nlm.nih.gov/15004150 II. Vertuani S, Triulzi C, Roos AK, Pisa P, Tullus C, Lindencrona JA, Charo J, Lemmonier F, Whitton JL, Nishimura MI, Seliger B, Kiessling R (2006). HER-2/neu mediated down-regulation of MHC class I antigen processing prevents CTL-mediated tumor recognition upon DNA vaccination in human HLA-A2 transgenic mice. [Manuscript]III. Vertuani S, De Geer A, Levitsky V, Kogner P, Kiessling R, Levitskaya J. (2003). Retinoids act as multistep modulators of the major histocompatibility class I presentation pathway and sensitize neuroblastomas to cytotoxic lymphocytes. Cancer Res. 63(22): 8006-13. https://pubmed.ncbi.nlm.nih.gov/14633733 IV. Vertuani S, Dubrovska E, Levitsky V, Jager MJ, Kiessling R, Levitskaya J (2006). Retinoic acid elicits cytostatic, cytotoxic and immunomodulatory effects on uveal melanoma cells. Cancer Immune Immunother. [Accepted] https://pubmed.ncbi.nlm.nih.gov/16752155 </p
Proteasome inhibitors reconstitute the presentation of cytotoxic T-cell epitopes in Epstein-Barr virus-associated tumors
No full textEBV-infected cells and EBV-associated tumors may evade CTL recognition by defective antigen processing, resulting in poor presentation of CTL epitopes. Since the proteasome is the major source of MHC class I-presented peptides, we analyzed the effect of proteasome inhibitors on the expression of surface HLA class I and the generation of EBV-derived CTL epitopes presented by the HLA-A2 and HLA-A11 alleles. Treatment with covalent and reversible inhibitors of the proteasome partially reduced the total and allele-specific expression of surface HLA class I in EBV-carrying LCLs. HLA-A2 expression was also decreased by treatment with leupeptin and bestatin, while HLA-A11 expression was affected by treatment with phenanthroline. Despite their general inhibitory effect on HLA class I expression, all proteasome inhibitors tested enhanced the presentation of 2 subdominant HLA-A2 epitopes from EBV LMP1 and LMP2, while the presentation of the immunodominant HLA-A11-restricted epitope from EBNA4 was inhibited by MG132 and lactacystin and increased by ZL3VS. Treatment with ZL3VS restored the presentation of endogenously expressed EBNA4 in I HLA-A11-positive BL cell line. These findings suggest that specific inhibitors of the proteasome may be used to increase the antigenicity of virus-infected and malignant cells that are per se inefficient at generating particular CTL target epitopes. © 2002 Wiley-Liss, Inc
Comparative antioxidant activity of tocotrienols and the novel chromanyl-polyisoprenyl molecule FeAox-6 in isolated membranes and intact cells
No full textOxidative stress plays a pivotal role in the pathogenesis of several chronic diseases and antioxidants may represent potential tools for the prevention of these diseases. Here, we investigated the antioxidant efficiency of different tocotrienol isoforms (é-, δ-, γ-tocotrienols), and that of FeAox-6, a novel synthetic compound which combines, by a stable covalent bond, the chroman head of vitamin E and a polyisoprenyl sequence of four conjugated double bonds into a single molecule. The antioxidant efficiency was evaluated as the ability of the compounds to inhibit lipid peroxidation, reactive oxygen species (ROS) production, heat shock protein (hsp) expression in rat liver microsomal membranes as well as in RAT-1 immortalized fibroblasts challenged with different free radical sources, including 2,2′-azobis(2-amidinopropane) (AAPH), tert-butyl hydroperoxide (tert-BOOH) and H2O2. Our results show that individual tocotrienols display different antioxidant potencies. Irrespective of the prooxidant used, the order of effectiveness was:δ-tocotrienol > γ-tocotrienol = é-tocotrienol in both isolated membranes and intact cells. This is presumably due to the decreased methylation of δ-tocotrienol chromane ring, which allows the molecule to be more easily incorporated into cell membranes. Moreover, we found that FeAox-6 showed an antioxidant potency greater than that of δ-tocotrienol. Such an efficiency seems to depend on the concomitant presence of a chromane ring and a phytyl chain in the molecule, which because of four conjugated double bonds, may induce a greater mobility and a more uniform distribution within cell membrane. In view of these results, FeAox-6 represents a new potential preventive agent in chronic diseases in which oxidative stress plays a pathogenic rol
Comparative antioxidant activity of tocotrienols and the novel chromanyl-plyisoprenyl molecule FeAox-6 in isolated membranes and intact cells.
No full textOxidative stress plays a pivotal role in the pathogenesis of several chronic diseases and antioxidants may represent potential tools for the prevention of these diseases. Here, we investigated the antioxidant efficiency of different tocotrienol isoforms (alpha-, delta-, gamma-tocotrienols), and that of FeAox-6, a novel synthetic compound which combines, by a stable covalent bond, the chroman head of vitamin E and a polyisoprenyl sequence of four conjugated double bonds into a single molecule. The antioxidant efficiency was evaluated as the ability of the compounds to inhibit lipid peroxidation, reactive oxygen species (ROS) production, heat shock protein (hsp) expression in rat liver microsomal membranes as well as in RAT-1 immortalized fibroblasts challenged with different free radical sources, including 2,2'-azobis(2-amidinopropane) (AAPH), tert-butyl hydroperoxide (tert-BOOH) and H2O2. Our results show that individual tocotrienols display different antioxidant potencies. Irrespective of the prooxidant used, the order of effectiveness was: delta-tocotrienol > gamma-tocotrienol = alpha-tocotrienol in both isolated membranes and intact cells. This is presumably due to the decreased methylation of delta-tocotrienol chromane ring, which allows the molecule to be more easily incorporated into cell membranes. Moreover, we found that FeAox-6 showed an antioxidant potency greater than that of delta-tocotrienol. Such an efficiency seems to depend on the concomitant presence of a chromane ring and a phytyl chain in the molecule, which because of four conjugated double bonds, may induce a greater mobility and a more uniform distribution within cell membrane. In view of these results, FeAox-6 represents a new potential preventive agent in chronic diseases in which oxidative stress plays a pathogenic role
c-myc overexpression activates alternative pathways for intracellular proteolysis in lymphoma cells
No full textBurkitt's lymphoma (BL) is a highly malignant B-cell tumour characterized by chromosomal translocations that constitutively activate the c-myc oncogene. Here we show that BL cells are resistant to apoptosis and do not accumulate ubiquitin conjugates in response to otherwise toxic doses of inhibitors of the proteasome. Deubiquitinating enzymes and the cytosolic subtilisin-like protease tripeptidylpeptidase II are upregulated in BLs, and could be rapidly induced by the overexpression of c-myc in normal B cells carrying oestrogen-driven recombinant Epstein-Barr virus. Apoptosis was induced by inhibiting tripeptidylpeptidase II, suggesting that the activity of this protease may be required for the survival of BL cells. We thus show that there is a regulatory link between c-myc activation and changes in proteolysis that may affect malignant transformation
A systematic literature review of time to return to work and narcotic use after lumbar spinal fusion using minimal invasive and open surgery techniques
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Additional file 5 of Overall survival of individuals with metastatic cancer in Sweden: a nationwide study
No full textAdditional file 5: Table 7. Coxregression analysis, metastatic ovarian cancer
Additional file 7 of Overall survival of individuals with metastatic cancer in Sweden: a nationwide study
No full textAdditional file 7: Table 9. Overviewof best fitting mixture cure models for all indication
Abstract PS5-44: Pik3ca mutations among hormone receptor positive and HER-2 negative advanced breast cancer patients in Finland
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